The only thing we fear is fear itself. —— Roosevelt
Everyone is more or less afraid of things, such as "height" (axial phobia), "deep" ( deep-sea phobia ), "space" (cluophobia)... The small ones are afraid of snakes, cockroaches, spiders, dogs, and caterpillars...

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This fear is interpreted as a way to protect oneself. Our bodies warn us that there is "dangerous" ahead and that if we continue, we will be "harmed", so we develop an emotion called "fear" to stop ourselves and avoid risking ourselves.
Our subconscious is a complete discourse system of "seeking profits and avoiding harm". We always want to make profits, and at the same time we are avoiding harm. Our genes are naturally imprinted with the "life instinct". Whether we live or act, we operate in an undetectable way under the framework of "survival".
Only when you are alive can you have everything.
This is something we don’t need to think about it deliberately, pay attention to it, or even learn it deliberately. We don’t remind ourselves all the time, and “I’m still alive” is always happening when our lives disappear.
If we regard living as a state that needs to be maintained, then those that are enough to destroy our lives are what we have been subconsciously avoiding. It is worth noting that we do not feel anything in this process. When we realize that we have to take action to maintain our "living" state, it means that we are indeed in great danger.
encounters danger, and we will subconsciously avoid it. Because we need to maintain our "living" state. In the repeated process of encountering dangers and avoiding dangers, we began to learn a key skill, which is "early warning".

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When any danger comes, no matter how we deal with it, we may lose our lives, whether it is our own or others. Therefore, animals "awaken" the ability of [danger perception]. Avoiding dangers in advance can save a lot of resources, which can further ensure the survival of individuals and even the entire species.
Then "fear" is the direct manifestation of this perception. Because animals develop fear, they can "bypass danger" in advance. In nature, this is exactly the behavior of running away after hearing/seeing natural enemies.
However, for humans, "danger" is far more than "natural disasters" and "natural enemies appear". As the human world continues to open up spaces known as "cultural symbols" based on nature, the "danger" faced by humans has become more "man-made disasters". "Man-made disasters" are far more than just "the same threat to humanity".

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Just as human cultural structure is complex, threats from humans, threats from intangible things created by humans, threats from tangible things created by humans, threats from tangible things created by humans, this can be language, words, symbols, spirits, or weapons, buildings, traps...
Therefore, human fear is more complex and more difficult to analyze.